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Use of quantitative bacteriologic techniques to diagnose catheter-related sepsis.

A case of polymicrobial sepsis occurred in a patient who had a permanent indwelling hyperalimentation catheter. Because it was undesirable to remove the catheter, quantitative bacteriologic techniques were used to determine whether the catheter was the source of sepsis. Blood drawn from a peripheral vein had 25 colonies per milliliter whereas blood drawn through the catheter had more than 10,000 colonies per milliliter. On the basis of these results, the catheter was removed. The catheter tip was found to be infected with the same organisms that were present in the blood. Quantitative bacteriologic techniques may prove useful in diagnosing catheter-related sepsis when it is undesirable to remove the catheter.

Adult

[Quantitative evaluation methods of the chemoantibiotic associations (author's transl)].

In the introductory part a new classification of joint drug actions is submitted, according which three fundamental types are distincted, named respectively interference, cooperation and true interaction. In its turn, interaction is subdivided in three classes (uni-effectual, bis-ineffectual, bis-effectual) in the last of which is placed the most relevant of the interactions, that is synergism, subclassified, at its turn, as additive, super and infra-additive. The second part is devoted to the classification of the bacteriological techniques hitherto proposed in order to evaluate in vitro and in vivo the antibacterial interaction of chemoantibiotics. The third part is devoted to the classification and critical analysis of biometrical techniques hitherto applied to above quoted bacteriological techniques in order to obtain a quantitative evaluation of interaction. Criticism versus isobolic model is pointed out. In the final part a new procedure, named isoeffectual, is proposed. According to such a procedure a close grid of single and joint concentrations of a couple of chemoantibiotics, broad enough in order to cover the whole of the effects to be explored, is tested in vitro adopting the one-center agar diffusion test or a liquid medium. The experimental data so obtained are related in a planar diagram to the log of the sum obtained by adding to the concentrations of the first the concentrations of the second agent, converted into equi-effectual concentrations of the first. By this way a series of curvilinear regressions is obtained, which may be all explained by a mathematical formula according which the data may be submitted to statistical analysis and elaborated in order to draw the parameters able to define quantitatively the interaction. The model so applied is discussed as a general model for joint drug action.

Anti-Bacterial Agents

[Urinary infection in urology. A rapid technique for confirmation of the diagnosis and the orientation of medical treatment (author's transl)].

A rapid technique for confirmation of the diagnosis and the orientation of medical treatment of urinary infection. Performance of direct antibiotic sensitivities on urine is a rapid (14 to 18 hours) procedure for determining the presence of organisms in the urine and seeking the antibiotic most active against them. In order to assess the value of the procedure, it was compared with classical bacteriological techniques. The correlation was found to be satisfactory. This procedure of direct sensitivity studies on urine is not in to way in competition with classical bacteriological techniques but is of great value in rapidly confirming the diagnosis of urinary infection and in the orientation of therapy. It eliminates a number of the justifications of blind treatment.

Anti-Bacterial Agents

Diagnosis of acute bacterial pneumonia in Nigerian children. Value of needle aspiration of lung of countercurrent immunoelectrophoresis.

Eighty-eight Nigerian children with untreated, severe, acute pneumonia were investigated by standard bacteriological techniques (blood culture and culture of pharyngeal secretions) and by needle aspiration of the consolidated lung. Countercurrent immunoelectrophoresis (CIE) against grouped pneumococcal and Haemophilus influenzae type b antisera was carried out on serum samples from 45 patients. The aetiology of pneumonia was shown by examination of the needle aspirate in 70/88 patients (79%), by CIE in 9/45 patients (20%), and by blood culture in 4/36 patients (11%). Overall, a bacterial cause for pneumonia was shown in 73/88 patients (83%). The results of pharyngeal culture were misleading when compared with cultures of needle aspirates. The prediction of aetiology from the radiological appearance was alos inaccurate, even for labor pneumonia. Needle aspiration of the lung, with a low (5%) and minor complication rate, merits wider application in the diagnosis of acute pulmonary infections in children. Tradiational bacteriological techniques (blood culture and pharyngeal culture) are of very limited value. The place of CIE in the investigation of childhood pneumonia still needs thorough evaluation.

Acute Disease

[The rapid detection and specific identification of bacterial antigens by electro-immunodiffusion in 80 cases of purulent meningitis (author's transl)].

The cerebrospinal fluid of 120 subjects, 80 of whom were suffering from a purulent meningitis, were examined comparatively by classical bacteriological techniques (direct examination and culture) and by electro-immunodiffusion. This procedure makes it possible to detect not only viable bacteria, but also capsular polysaccharide antigens. It revealed the diagnosis in 96.9% of cases of meningococcal, pneumococcal and Haemophilus meningitis, as against 80.3% positive results using classical bacteriological techniques, for the same organisms. Electro-immunodiffusion provides a rapid answer (20 minutes) and, amongst other things, makes it possible: - to confirm the serotype or capsular type within the species, - to determine the aetiological diagnosis in certain types of meningitis where diagnosis is rendered difficult by blind antibiotic therapy, - to quantify and follow over a period of time the levels of polysaccharide antigens in the cerebrospinal fluid and serum of the patients. The sensitivity and specificity of electro-immunodiffusion render it a technique of the future in the diagnosis of purulent meningitis. By virtue of its simplicity, it should become a routine examination.

Antigens, Bacterial

Bacteriology of the chronically discharging middle ear.

Suitable bacteriological techniques revealed anaerobic bacteria in 38 (33%) of 114 chronically discharging middle ears. The genus Bacteroides was cultured from 25 ears. Aerobic bacteriology showed the predominance of staphylococci, facultative enteric gramnegative rods, diphtheroid bacilli and Pseudomonas species. Anaerobic bacterial cultures were always mixed with aerobic bacteria. 12 ears were culture-negative, and 9 of the 108 Gram-stained smers revealed no bacteria. No significant difference in bacteriology was noted between ears with or without local antimicrobial treatment, or between profusely draining or only moist ears. The ears with postoperative recurrent infection or with clinical suspicion of cholesteatoma grew anaerobes significantly more often, and were seldom sterile. Because anaerobic bacteria are frequently associated with chronic otitis media, their characteristics with regard to susceptibility to antimicrobials and to air must be remembered in the choice of therapy.

Bacteria

Isolation of Mycoplasma hominis from blood cultures in patients with postpartum fever.

Eight women with postpartum fever are presented in whom Mycoplasma hominis was isolated from cultures of their blood. Clinical disease consisted of a mild although often prolonged febrile illness, and all but one recovered without appropriate antimicrobial therapy. Five patients demonstrated elevated convalescent titers of mycoplasmacidal antibodies. The isolates of M. hominis were recovered from routine blood cultures in the diagnostic bacteriology laboratory using blind subcultures to blood agar plates. These cases lend support to the concept that endometritis with M. hominis is a cause of postpartum fever and suggest that these organisms may be recovered with increased frequency if minor changes in standard bacteriologic technique are introduced.

Bacteriological Techniques

Wound infections and systemic antibiotic prophylaxis in gynecologic surgery. A review.

The gynecologic literature was reviewed and yielded 11 well-designed and well-conducted studies since 1960 involving the use of systemic prophylactic antibiotics. Five had significant results that support using prophylactic antibiotics in vaginal hysterectomy while three supported prophylaxis in cesarean sections. A cephalosporin agent is effective as a prophylactic agent and should be administered 2 hours before surgery by the intravenous route and discontinued 24-72 hours after surgery. A change in the bacteriologic flora of the cervical cuff occurs after surgery with an increase in E. coli and enterococci and a decrease in coagulose negative staphylococci and steptococci. Future studies should be randomized, prospective, and performed in a double-blind manner with antibiotics begun preoperatively. Special attention should be given to bacteriologic techniques, especially the search for anaerobic pathogens.

Anti-Bacterial Agents

Improving isolate recovery and identification of the Shiga toxin type in Shiga toxin nucleic acid test-positive feces.

UNLABELLED: Infections caused by Shiga toxin-producing Escherichia coli (STEC) strains carrying Shiga toxin 2 (stx2) are more likely to result in severe complications; however, most nucleic acid amplification tests used for STEC diagnosis do not differentiate between stx1 and stx2. We therefore sought to optimize stx typing and isolate recovery methods to guide clinical and public health management. stx polymerase chain reaction (PCR)-positive feces were cultured using CHROMagar STEC and gram-negative broth, with Stx1 and/or Stx2 antigen detection by enzyme immunoassay (EIA) on colony growth or turbid broth. When cultures were EIA-negative, growth from MacConkey agar (MAC), Trypticase soy broth, and the gram-negative broth was then tested using a lab-developed typing PCR for stx1 and stx2. Colonies were isolated on CHROMagar STEC or MAC and identified using the typing PCR. Using both EIA and typing PCR, the stx types were identified in 96.0% of cases (381/397). In 65.2% (259/397) of cases, culture was EIA-positive, of which 34.0% (87/256) were Stx2-positive. Among cultures that were EIA-negative but typing PCR-positive, 64.8% (79/122) were stx2-positive (P < 0.0001 compared to EIA-positive). Using both EIA and typing PCR resulted in 72.6% (286/394) of cases with successful attempts at isolate recovery, compared to 60.7% (239/394) with EIA alone. E. coli O157 was recovered from more EIA-positive cases (19.3%, 46/239) than EIA-negative ones (4.3%, 2/47) (P = 0.0097). Typing PCR on cultures improves stx typing (particularly stx2) and isolate detection compared to EIA alone. Screening BD Max PCR and subsequent typing PCR results showed excellent concordance. IMPORTANCE: Escherichia coli strains with one or both types of Shiga toxins (stx1 and stx2) are a common cause of bacterial diarrhea and can lead to serious complications such as kidney failure, especially in children. Infection by stx2-positive strains is more likely to do so. Therefore, knowing whether the infection is caused by a strain carrying stx2 is important for risk assessment and case follow-up. The conventional way to diagnose these infections is to grow the bacteria from stool, but most laboratories currently use nucleic acid detection (e.g., bacterial DNA detection by polymerase chain reaction [PCR]), and these assays do not differentiate between the two toxin genes. Culture is therefore required to determine toxin type, as well as for public health outbreak investigations, which require an isolate for whole-genome sequencing for serotyping and cluster analysis. We identified culture media and a PCR-based method to detect stx2 in culture that improved the detection of stx2 and isolate recovery. Our findings provide more accurate results for clinicians to improve patient care and tools for public health teams to control and prevent outbreaks.

Humans

Effect of a Ca(OH)2 solution and a chlorhexidine based detergent on the microbial activity of human carious teeth.

Occlusar carious lesions from human molars, preserved in continuous humidity after extraction, were removed using conventional clinical techniques. Bacteriological samples were taken after rinsing the cavity with water only, after experimentally infecting the cavity and after treating uninfected cavities either with a saturated Ca(OH)2 solution or with a chlorhexidine based detergent. The samples were cultivated on blood agar plates aerobically and anaerobically. Cavities rinsed with water only showed very sparce bacterial growth. After experimental infection the growth was significant, but decreased radically after treatment with the test materials. In order to describe the effect of the two test materials on the microbial enzyme activity in infected dentin, cryostat sections of 10 micrometer were prepared from undermineralized carious dentin fragments excavated from freshly extracted human teeth. Conventional histochemical techniques were applied to demonstrate the aminopeptidase activity in the sections using N-L-leucyl-2-naphthylamide as a substrate. The aminopeptidase activity of carious dentin was inhibited totally with the Ca(OH)2 solution, whereas the chlorhexidine based detergent had no effect on the enzyme activity.

Aminopeptidases

Staphylococcal septic arthritis in three horses.

Three horses were diagnosed as having monarticular septic arthritis due to Staphylococcus aureus on the basis of culture of articular cartilage, synovial membrane and/or synovial fluid. The organisms were all well recognised human phage types and in two cases demonstrated beta-lactamase (penicillinase) activity. Details of case histories are presented and the bacteriological techniques and antibiotic management with cloxacillin, methicillin and penicillin discussed. Following treatment, sterile cultures of synovial fluid were achieved in all cases, but in two horses the infections resulted in degenerative articular changes. This necessitated arthrodesis of the fetlock joint in one case.

Animals

Biochemical pharmacology of the intestinal flora.

Animal and bacteriological techniques have been developed for clarifying the role of the flora in the metabolism of drugs and other exogenous compounds. In general the flora tends to catalyze reductive and hydrolytic reactions, some of which reverse the detoxification reactions normally occurring in the liver. These reactions and others have been implicated in the pharamacological or toxicological action of exogenous compounds. Only in a few instances, however, have practical consequences of these reactions been documented. The major challenge at present is to develop methods capable of further defining the implications of reactions due to the flora.

Animals

The bacteriology of perimandibular space infections.

The bacteriology of 21 perimandibular clised-space infections was studied prospectively using optimal bacteriological techniques to collect, transport, and process specimens. There was an average of six microbial species per specimen, including approximately four anaerobes and two aerobes. The predominant aerobes were alpha-hemolytic and non-hemolytic streptococci; the predominant anaerobes were peptostreptococci, Bacteroides melaninogenicus, and Fusobacterium nucleatum. These findings indicate that most perimandibular space infections involve a polymicrobial flora in which anaerobic bacteria are the dominant isolates. Antimicrobial decisions should account for these observations, particularly in cases where cultural data are not available or when anaerobic cultures are not performed with optimal techniques.

Adult

[Current problems of medical microbiology: Achievements, tasks and perspectives].

Two important problems of current medical microbiology are discussed in this paper: 1) a change of etiological structure of infectious morbidity-elevation of the incidence of infections caused by conditioned pathogenic causative agents, and 2) postvaccinal complications. In the light of these problems the tasks of microbiological investigations for the immediate future are discussed. Tasks and prospects of study of the molecular structure of the pathogenicity factors of importance for the creation of chemical vaccines and genetic investigations which would provide construction of strains and preparations useful in practice are formulated.

Bacteriological Techniques